Perhaps you should try some spelling variations:
tham thuc » nham thuc, tam thuc, thai thuc
pham thuc » phap thuc, pham chuc, nham thuc
lieu van » lieu va, hieu van, sieu van
hang dai » hoang dai, hang tai, hang dau
vu nang » vuc nang, vu dang, v nang
va nang » van nang, da nang, cam nang
va hang » van hang, va lang, va hanh
cua tre » cua te, cuu tre, cua triet

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sinh ((vu nang) or (va nang)) xa hoi. lieu van ((tham thuc) OR (pham thuc)) va hang dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sinh ((vu nang) OR (va nang)) xa hoi. lieu van ((tham thuc) OR (pham thuc)) va hang dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sinh ((vu nang) or (va nang)) xa hoi. lieu van ((tham thuc) OR (pham thuc)) va hang dai cua tre".
• Adding a wildcard symbol may retrieve word variants: hoc sinh ((vu nang) or (va nang)) xa hoi. lieu van ((tham thuc) OR (pham thuc)) va hang dai cua tre*.